Fibroadenomas are non malignant neoplasms constituted by a proliferation of connective and epithelial tissue in variable proportions. Its incidence is greater in the second and third decades of life although they can appear at any age.
It is a well known fact that carcinoma may develop inside 0.2-2% of fibroadenomas. In ninety five percent of cases the carcinomas are non invasive, lobulillar type being more frequent than ductal. Mean age in this group being 20 years older than those with non-malignant fibroadenomas.